The pouring of low slump concrete into forms to build sidewalks, patios, roads, ramps, bridges, and the like is well known. It is also known to reinforce low slump concrete by the use of reinforcing rods made of steel or the like, the rods being placed into the forms prior to the pouring of the concrete and being held in elevated altitude in the forms by plastic inserts or such so that the rods are ultimately embedded in the set concrete.
It is further known to vibrate the concrete by inserting into or placing onto the concrete, before it has set, a mechanical vibrator. The function of the vibrator is to vibrate the concrete so that air and voids are eliminated therefrom to avoid the formation of undesirable pockets or honeycombs in the hardened concrete.
It has been found than, after a number of years, reinforcing rods may corrode thus weakening the thusly formed construction. This will especially happen under, for example, conditions whereby salt is spread in the winter to prevent the formation of ice. It will also happen due to the prevalence of acid rain and in ocean front structures, and so forth. To avoid the corrosion of reinforcing rods, they have been coated with a non-corrosive coating such as 0.005 to 0.010 inches of epoxy to shield them from the action of corrosive substances. This coating is frequently destroyed or marred upon being contacted by a vibrator which is being used as indicated above.
In my earlier U.S. Pat. No. 5,108,189 is disclosed a vibrator which includes a relatively rigid shell having therein a vibrating mechanism to enable the vibrator to vibrate. The shell in said patent is provided with a cover which is formed of a material softer than the shell to lessen the effect of the impact of the shell on rigid objects encountered by the vibrator. Such rigid objects may be, for example, reinforcing rods covered with an epoxy the chipping of which is to be avoided. The preferred form of the vibrator of said patent provided passages through which wet concrete could find access to the shell to remove heat therefrom. More particularly, an undercut in such passages was provided in order to expose an increased area of the shell to the cooling effect of the wet concrete.
It has now been found that, in certain circumstances and between sequential uses of a vibrator of the aforenoted type, some of the wet concrete will be cured and thus will harden. The hardened concrete may be undesirably retained in the passages which otherwise advantageously provide access to the shell for cooling purposes.